fix(runfiles): assume main repository on Windows (#3578)

With any Python version on Windows, `RUNFILES_*` environment variables
still point to an intermediate stage path instead of the module path,
causing `CurrentRepository()` to raise a `ValueError` since
`rules_python` v1.8.0:
```
ValueError: C:\Users\bot\AppData\Local\Temp\Bazel.runfiles_gh34ij5_\runfiles\+_repo_rules+cpython\my_script.py does not lie under the runfiles root C:/cache/ab1cdef2/execroot/_main/bazel-out/x64_windows-fastbuild/bin/external/+_repo_rules+cpython/install.exe.runfiles
```

This was not the case with `rules_python` v1.7.0. The issue stems from
behavior.

Since #3086 came up with a corresponding workaround in
`//tests/runtime_env_toolchain:toolchain_runs_test`, the proposed fix
simply consists in moving it to `CurrentRepository()`, thus adding
another case to the workaround introduced by #1634 for Python < 3.11. It
therefore leads to assuming the main module path on Windows as well.

Removing the workaround from `CurrentRepository()` would make the test
fail as follows:
```
==================== Test output for //tests/runtime_env_toolchain:toolchain_runs_test:
E
======================================================================
ERROR: test_ran (__main__.RunTest.test_ran)
----------------------------------------------------------------------
Traceback (most recent call last):
[...]
ValueError: C:\Users\user\AppData\Local\Temp\Bazel.runfiles_1f08smy6\runfiles\_main\tests\runtime_env_toolchain\toolchain_runs_test.py does not lie under the runfiles root c:\users\user\_bazel_user\cxxeswjo\execroot\_main\bazel-out\x64_windows-fastbuild-st-c530e4918e48\bin\tests\runtime_env_toolchain\toolchain_runs_test.exe.runfiles
```

Fixes #3579.

(cherry picked from commit f78add7)

Author: rdesgroppes

CHANGELOG.md

@@ -47,6 +47,17 @@ BEGIN_UNRELEASED_TEMPLATE
 END_UNRELEASED_TEMPLATE
 -->
 
+
+{#v1-8-5}
+## [1.8.5] - 2026-02-22
+
+[1.8.5]: https://github.com/bazel-contrib/rules_python/releases/tag/1.8.5
+
+{#v1-8-5-fixed}
+### Fixed
+* (runfiles) Fixed `CurrentRepository()` raising `ValueError` on Windows.
+  ([#3579](https://github.com/bazel-contrib/rules_python/issues/3579))
+
 {#v1-8-4}
 ## [1.8.4] - 2026-02-10
 

python/runfiles/runfiles.py

@@ -389,11 +389,15 @@ def CurrentRepository(self, frame: int = 1) -> str:
             # located in the main repository.
             # With Python 3.11 and higher, the Python launcher sets
             # PYTHONSAFEPATH, which prevents this behavior.
+            # On Windows, the current toolchain being used has a buggy zip file
+            # bootstrap, which leaves RUNFILES_DIR pointing at the first stage
+            # path and not the module path. In this case too, assume that the
+            # module is located in the main repository.
             # TODO: This doesn't cover the case of a script being run from an
             #       external repository, which could be heuristically detected
             #       by parsing the script's path.
             if (
-                sys.version_info.minor <= 10
+                (sys.version_info.minor <= 10 or sys.platform == "win32")
                 and sys.path[0] != self._python_runfiles_root
             ):
                 return ""

tests/runtime_env_toolchain/toolchain_runs_test.py

@@ -10,18 +10,9 @@
 class RunTest(unittest.TestCase):
     def test_ran(self):
         rf = runfiles.Create()
-        try:
-            settings_path = rf.Rlocation(
-                "rules_python/tests/support/current_build_settings.json"
-            )
-        except ValueError as e:
-            # The current toolchain being used has a buggy zip file bootstrap, which
-            # leaves RUNFILES_DIR pointing at the first stage path and not the module
-            # path.
-            if platform.system() != "Windows" or "does not lie under the runfiles root" not in str(e):
-                raise e
-            settings_path = "./tests/support/current_build_settings.json"
-
+        settings_path = rf.Rlocation(
+            "rules_python/tests/support/current_build_settings.json"
+        )
         settings = json.loads(pathlib.Path(settings_path).read_text())
 
         if platform.system() == "Windows":